16 "github.com/RoaringBitmap/roaring"
17 "github.com/anacrolix/log"
18 "github.com/anacrolix/missinggo/iter"
19 "github.com/anacrolix/missinggo/v2/bitmap"
20 "github.com/anacrolix/multiless"
22 "github.com/anacrolix/chansync"
23 "github.com/anacrolix/torrent/bencode"
24 "github.com/anacrolix/torrent/metainfo"
25 "github.com/anacrolix/torrent/mse"
26 pp "github.com/anacrolix/torrent/peer_protocol"
27 request_strategy "github.com/anacrolix/torrent/request-strategy"
30 type PeerSource string
33 PeerSourceTracker = "Tr"
34 PeerSourceIncoming = "I"
35 PeerSourceDhtGetPeers = "Hg" // Peers we found by searching a DHT.
36 PeerSourceDhtAnnouncePeer = "Ha" // Peers that were announced to us by a DHT.
38 // The peer was given directly, such as through a magnet link.
39 PeerSourceDirect = "M"
42 type peerRequestState struct {
46 type PeerRemoteAddr interface {
50 // Since we have to store all the requests in memory, we can't reasonably exceed what would be
51 // indexable with the memory space available.
54 requestState = request_strategy.PeerNextRequestState
58 // First to ensure 64-bit alignment for atomics. See #262.
68 RemoteAddr PeerRemoteAddr
69 // True if the connection is operating over MSE obfuscation.
71 cryptoMethod mse.CryptoMethod
74 closed chansync.SetOnce
75 // Set true after we've added our ConnStats generated during handshake to
76 // other ConnStat instances as determined when the *Torrent became known.
77 reconciledHandshakeStats bool
79 lastMessageReceived time.Time
80 completedHandshake time.Time
81 lastUsefulChunkReceived time.Time
82 lastChunkSent time.Time
84 // Stuff controlled by the local peer.
85 needRequestUpdate string
86 actualRequestState requestState
87 updateRequestsTimer *time.Timer
88 cancelledRequests roaring.Bitmap
89 lastBecameInterested time.Time
90 priorInterest time.Duration
92 lastStartedExpectingToReceiveChunks time.Time
93 cumulativeExpectedToReceiveChunks time.Duration
94 _chunksReceivedWhileExpecting int64
97 piecesReceivedSinceLastRequestUpdate maxRequests
98 maxPiecesReceivedBetweenRequestUpdates maxRequests
99 // Chunks that we might reasonably expect to receive from the peer. Due to
100 // latency, buffering, and implementation differences, we may receive
101 // chunks that are no longer in the set of requests actually want.
102 validReceiveChunks map[RequestIndex]int
103 // Indexed by metadata piece, set to true if posted and pending a
105 metadataRequests []bool
106 sentHaves bitmap.Bitmap
108 // Stuff controlled by the remote peer.
111 peerRequests map[Request]*peerRequestState
112 PeerPrefersEncryption bool // as indicated by 'e' field in extension handshake
114 // The pieces the peer has claimed to have.
115 _peerPieces roaring.Bitmap
116 // The peer has everything. This can occur due to a special message, when
117 // we may not even know the number of pieces in the torrent yet.
119 // The highest possible number of pieces the torrent could have based on
120 // communication with the peer. Generally only useful until we have the
122 peerMinPieces pieceIndex
123 // Pieces we've accepted chunks for from the peer.
124 peerTouchedPieces map[pieceIndex]struct{}
125 peerAllowedFast roaring.Bitmap
127 PeerMaxRequests maxRequests // Maximum pending requests the peer allows.
128 PeerExtensionIDs map[pp.ExtensionName]pp.ExtensionNumber
129 PeerClientName string
134 // Maintains the state of a BitTorrent-protocol based connection with a peer.
135 type PeerConn struct {
138 // A string that should identify the PeerConn's net.Conn endpoints. The net.Conn could
139 // be wrapping WebRTC, uTP, or TCP etc. Used in writing the conn status for peers.
144 PeerExtensionBytes pp.PeerExtensionBits
146 // The actual Conn, used for closing, and setting socket options.
148 // The Reader and Writer for this Conn, with hooks installed for stats,
149 // limiting, deadlines etc.
153 messageWriter peerConnMsgWriter
155 uploadTimer *time.Timer
159 func (cn *PeerConn) connStatusString() string {
160 return fmt.Sprintf("%+-55q %s %s", cn.PeerID, cn.PeerExtensionBytes, cn.connString)
163 func (cn *Peer) updateExpectingChunks() {
164 if cn.expectingChunks() {
165 if cn.lastStartedExpectingToReceiveChunks.IsZero() {
166 cn.lastStartedExpectingToReceiveChunks = time.Now()
169 if !cn.lastStartedExpectingToReceiveChunks.IsZero() {
170 cn.cumulativeExpectedToReceiveChunks += time.Since(cn.lastStartedExpectingToReceiveChunks)
171 cn.lastStartedExpectingToReceiveChunks = time.Time{}
176 func (cn *Peer) expectingChunks() bool {
177 if cn.actualRequestState.Requests.IsEmpty() {
180 if !cn.actualRequestState.Interested {
186 haveAllowedFastRequests := false
187 cn.peerAllowedFast.Iterate(func(i uint32) bool {
188 haveAllowedFastRequests = roaringBitmapRangeCardinality(
189 &cn.actualRequestState.Requests,
190 cn.t.pieceRequestIndexOffset(pieceIndex(i)),
191 cn.t.pieceRequestIndexOffset(pieceIndex(i+1)),
193 return !haveAllowedFastRequests
195 return haveAllowedFastRequests
198 func (cn *Peer) remoteChokingPiece(piece pieceIndex) bool {
199 return cn.peerChoking && !cn.peerAllowedFast.Contains(bitmap.BitIndex(piece))
202 // Returns true if the connection is over IPv6.
203 func (cn *PeerConn) ipv6() bool {
208 return len(ip) == net.IPv6len
211 // Returns true the if the dialer/initiator has the lower client peer ID. TODO: Find the
212 // specification for this.
213 func (cn *PeerConn) isPreferredDirection() bool {
214 return bytes.Compare(cn.t.cl.peerID[:], cn.PeerID[:]) < 0 == cn.outgoing
217 // Returns whether the left connection should be preferred over the right one,
218 // considering only their networking properties. If ok is false, we can't
220 func (l *PeerConn) hasPreferredNetworkOver(r *PeerConn) (left, ok bool) {
222 ml.NextBool(l.isPreferredDirection(), r.isPreferredDirection())
223 ml.NextBool(!l.utp(), !r.utp())
224 ml.NextBool(l.ipv6(), r.ipv6())
228 func (cn *Peer) cumInterest() time.Duration {
229 ret := cn.priorInterest
230 if cn.actualRequestState.Interested {
231 ret += time.Since(cn.lastBecameInterested)
236 func (cn *Peer) peerHasAllPieces() (all bool, known bool) {
237 if cn.peerSentHaveAll {
240 if !cn.t.haveInfo() {
243 return roaring.Flip(&cn._peerPieces, 0, bitmap.BitRange(cn.t.numPieces())).IsEmpty(), true
246 func (cn *Peer) locker() *lockWithDeferreds {
247 return cn.t.cl.locker()
250 func (cn *Peer) supportsExtension(ext pp.ExtensionName) bool {
251 _, ok := cn.PeerExtensionIDs[ext]
255 // The best guess at number of pieces in the torrent for this peer.
256 func (cn *Peer) bestPeerNumPieces() pieceIndex {
258 return cn.t.numPieces()
260 return cn.peerMinPieces
263 func (cn *Peer) completedString() string {
264 have := pieceIndex(cn._peerPieces.GetCardinality())
265 if cn.peerSentHaveAll {
266 have = cn.bestPeerNumPieces()
268 return fmt.Sprintf("%d/%d", have, cn.bestPeerNumPieces())
271 func (cn *PeerConn) onGotInfo(info *metainfo.Info) {
272 cn.setNumPieces(info.NumPieces())
275 // Correct the PeerPieces slice length. Return false if the existing slice is invalid, such as by
276 // receiving badly sized BITFIELD, or invalid HAVE messages.
277 func (cn *PeerConn) setNumPieces(num pieceIndex) {
278 cn._peerPieces.RemoveRange(bitmap.BitRange(num), bitmap.ToEnd)
279 cn.peerPiecesChanged()
282 func eventAgeString(t time.Time) string {
286 return fmt.Sprintf("%.2fs ago", time.Since(t).Seconds())
289 func (cn *PeerConn) connectionFlags() (ret string) {
291 ret += string([]byte{b})
293 if cn.cryptoMethod == mse.CryptoMethodRC4 {
295 } else if cn.headerEncrypted {
298 ret += string(cn.Discovery)
305 func (cn *PeerConn) utp() bool {
306 return parseNetworkString(cn.Network).Udp
309 // Inspired by https://github.com/transmission/transmission/wiki/Peer-Status-Text.
310 func (cn *Peer) statusFlags() (ret string) {
312 ret += string([]byte{b})
314 if cn.actualRequestState.Interested {
321 ret += cn.connectionFlags()
323 if cn.peerInterested {
332 func (cn *Peer) downloadRate() float64 {
333 num := cn._stats.BytesReadUsefulData.Int64()
337 return float64(num) / cn.totalExpectingTime().Seconds()
340 func (cn *Peer) numRequestsByPiece() (ret map[pieceIndex]int) {
341 ret = make(map[pieceIndex]int)
342 cn.actualRequestState.Requests.Iterate(func(x uint32) bool {
343 ret[pieceIndex(x/cn.t.chunksPerRegularPiece())]++
349 func (cn *Peer) writeStatus(w io.Writer, t *Torrent) {
350 // \t isn't preserved in <pre> blocks?
351 if cn.closed.IsSet() {
352 fmt.Fprint(w, "CLOSED: ")
354 fmt.Fprintln(w, cn.connStatusString())
355 prio, err := cn.peerPriority()
356 prioStr := fmt.Sprintf("%08x", prio)
358 prioStr += ": " + err.Error()
360 fmt.Fprintf(w, " bep40-prio: %v\n", prioStr)
361 fmt.Fprintf(w, " last msg: %s, connected: %s, last helpful: %s, itime: %s, etime: %s\n",
362 eventAgeString(cn.lastMessageReceived),
363 eventAgeString(cn.completedHandshake),
364 eventAgeString(cn.lastHelpful()),
366 cn.totalExpectingTime(),
369 " %s completed, %d pieces touched, good chunks: %v/%v:%v reqq: %d-%v/(%d/%d):%d/%d, flags: %s, dr: %.1f KiB/s\n",
370 cn.completedString(),
371 len(cn.peerTouchedPieces),
372 &cn._stats.ChunksReadUseful,
373 &cn._stats.ChunksRead,
374 &cn._stats.ChunksWritten,
375 cn.actualRequestState.Requests.GetCardinality(),
376 cn.cancelledRequests.GetCardinality(),
377 cn.nominalMaxRequests(),
379 len(cn.peerRequests),
382 cn.downloadRate()/(1<<10),
384 fmt.Fprintf(w, " requested pieces:")
385 type pieceNumRequestsType struct {
389 var pieceNumRequests []pieceNumRequestsType
390 for piece, count := range cn.numRequestsByPiece() {
391 pieceNumRequests = append(pieceNumRequests, pieceNumRequestsType{piece, count})
393 sort.Slice(pieceNumRequests, func(i, j int) bool {
394 return pieceNumRequests[i].piece < pieceNumRequests[j].piece
396 for _, elem := range pieceNumRequests {
397 fmt.Fprintf(w, " %v(%v)", elem.piece, elem.numRequests)
402 func (p *Peer) close() {
406 if p.updateRequestsTimer != nil {
407 p.updateRequestsTimer.Stop()
411 p.t.decPeerPieceAvailability(p)
413 for _, f := range p.callbacks.PeerClosed {
418 func (cn *PeerConn) onClose() {
419 if cn.pex.IsEnabled() {
426 if cb := cn.callbacks.PeerConnClosed; cb != nil {
431 func (cn *Peer) peerHasPiece(piece pieceIndex) bool {
432 return cn.peerSentHaveAll || cn._peerPieces.Contains(bitmap.BitIndex(piece))
435 // 64KiB, but temporarily less to work around an issue with WebRTC. TODO: Update when
436 // https://github.com/pion/datachannel/issues/59 is fixed.
437 const writeBufferHighWaterLen = 1 << 15
439 // Writes a message into the write buffer. Returns whether it's okay to keep writing. Writing is
440 // done asynchronously, so it may be that we're not able to honour backpressure from this method.
441 func (cn *PeerConn) write(msg pp.Message) bool {
442 torrent.Add(fmt.Sprintf("messages written of type %s", msg.Type.String()), 1)
443 // We don't need to track bytes here because the connection's Writer has that behaviour injected
444 // (although there's some delay between us buffering the message, and the connection writer
445 // flushing it out.).
446 notFull := cn.messageWriter.write(msg)
447 // Last I checked only Piece messages affect stats, and we don't write those.
453 func (cn *PeerConn) requestMetadataPiece(index int) {
454 eID := cn.PeerExtensionIDs[pp.ExtensionNameMetadata]
455 if eID == pp.ExtensionDeleteNumber {
458 if index < len(cn.metadataRequests) && cn.metadataRequests[index] {
461 cn.logger.WithDefaultLevel(log.Debug).Printf("requesting metadata piece %d", index)
462 cn.write(pp.MetadataExtensionRequestMsg(eID, index))
463 for index >= len(cn.metadataRequests) {
464 cn.metadataRequests = append(cn.metadataRequests, false)
466 cn.metadataRequests[index] = true
469 func (cn *PeerConn) requestedMetadataPiece(index int) bool {
470 return index < len(cn.metadataRequests) && cn.metadataRequests[index]
473 // The actual value to use as the maximum outbound requests.
474 func (cn *Peer) nominalMaxRequests() (ret maxRequests) {
475 return maxRequests(clamp(1, int64(cn.PeerMaxRequests), 2048))
478 func (cn *Peer) totalExpectingTime() (ret time.Duration) {
479 ret = cn.cumulativeExpectedToReceiveChunks
480 if !cn.lastStartedExpectingToReceiveChunks.IsZero() {
481 ret += time.Since(cn.lastStartedExpectingToReceiveChunks)
487 func (cn *PeerConn) onPeerSentCancel(r Request) {
488 if _, ok := cn.peerRequests[r]; !ok {
489 torrent.Add("unexpected cancels received", 1)
492 if cn.fastEnabled() {
495 delete(cn.peerRequests, r)
499 func (cn *PeerConn) choke(msg messageWriter) (more bool) {
504 more = msg(pp.Message{
507 if cn.fastEnabled() {
508 for r := range cn.peerRequests {
509 // TODO: Don't reject pieces in allowed fast set.
513 cn.peerRequests = nil
518 func (cn *PeerConn) unchoke(msg func(pp.Message) bool) bool {
523 return msg(pp.Message{
528 func (cn *Peer) setInterested(interested bool) bool {
529 if cn.actualRequestState.Interested == interested {
532 cn.actualRequestState.Interested = interested
534 cn.lastBecameInterested = time.Now()
535 } else if !cn.lastBecameInterested.IsZero() {
536 cn.priorInterest += time.Since(cn.lastBecameInterested)
538 cn.updateExpectingChunks()
539 // log.Printf("%p: setting interest: %v", cn, interested)
540 return cn.writeInterested(interested)
543 func (pc *PeerConn) writeInterested(interested bool) bool {
544 return pc.write(pp.Message{
545 Type: func() pp.MessageType {
549 return pp.NotInterested
555 // The function takes a message to be sent, and returns true if more messages
557 type messageWriter func(pp.Message) bool
559 // This function seems to only used by Peer.request. It's all logic checks, so maybe we can no-op it
560 // when we want to go fast.
561 func (cn *Peer) shouldRequest(r RequestIndex) error {
562 pi := pieceIndex(r / cn.t.chunksPerRegularPiece())
563 if !cn.peerHasPiece(pi) {
564 return errors.New("requesting piece peer doesn't have")
566 if !cn.t.peerIsActive(cn) {
567 panic("requesting but not in active conns")
569 if cn.closed.IsSet() {
570 panic("requesting when connection is closed")
572 if cn.t.hashingPiece(pi) {
573 panic("piece is being hashed")
575 if cn.t.pieceQueuedForHash(pi) {
576 panic("piece is queued for hash")
578 if cn.peerChoking && !cn.peerAllowedFast.Contains(bitmap.BitIndex(pi)) {
579 // This could occur if we made a request with the fast extension, and then got choked and
580 // haven't had the request rejected yet.
581 if !cn.actualRequestState.Requests.Contains(r) {
582 panic("peer choking and piece not allowed fast")
588 func (cn *Peer) mustRequest(r RequestIndex) bool {
589 more, err := cn.request(r)
596 func (cn *Peer) request(r RequestIndex) (more bool, err error) {
597 if err := cn.shouldRequest(r); err != nil {
600 if cn.actualRequestState.Requests.Contains(r) {
603 if maxRequests(cn.actualRequestState.Requests.GetCardinality()) >= cn.nominalMaxRequests() {
604 return true, errors.New("too many outstanding requests")
606 cn.actualRequestState.Requests.Add(r)
607 if cn.validReceiveChunks == nil {
608 cn.validReceiveChunks = make(map[RequestIndex]int)
610 cn.validReceiveChunks[r]++
611 cn.t.pendingRequests.Inc(r)
612 cn.updateExpectingChunks()
613 ppReq := cn.t.requestIndexToRequest(r)
614 for _, f := range cn.callbacks.SentRequest {
615 f(PeerRequestEvent{cn, ppReq})
617 return cn.peerImpl._request(ppReq), nil
620 func (me *PeerConn) _request(r Request) bool {
621 return me.write(pp.Message{
629 func (me *Peer) cancel(r RequestIndex) bool {
630 if !me.actualRequestState.Requests.Contains(r) {
636 func (me *PeerConn) _cancel(r RequestIndex) bool {
637 if me.cancelledRequests.Contains(r) {
638 // Already cancelled and waiting for a response.
641 if me.fastEnabled() {
642 me.cancelledRequests.Add(r)
644 if !me.deleteRequest(r) {
645 panic("request not existing should have been guarded")
647 if me.isLowOnRequests() {
648 me.updateRequests("Peer.cancel")
651 return me.write(makeCancelMessage(me.t.requestIndexToRequest(r)))
654 func (cn *PeerConn) fillWriteBuffer() {
655 if !cn.maybeUpdateActualRequestState() {
658 if cn.pex.IsEnabled() {
659 if flow := cn.pex.Share(cn.write); !flow {
666 func (cn *PeerConn) have(piece pieceIndex) {
667 if cn.sentHaves.Get(bitmap.BitIndex(piece)) {
672 Index: pp.Integer(piece),
674 cn.sentHaves.Add(bitmap.BitIndex(piece))
677 func (cn *PeerConn) postBitfield() {
678 if cn.sentHaves.Len() != 0 {
679 panic("bitfield must be first have-related message sent")
681 if !cn.t.haveAnyPieces() {
686 Bitfield: cn.t.bitfield(),
688 cn.sentHaves = bitmap.Bitmap{cn.t._completedPieces.Clone()}
691 // Sets a reason to update requests, and if there wasn't already one, handle it.
692 func (cn *Peer) updateRequests(reason string) {
693 if cn.needRequestUpdate != "" {
696 cn.needRequestUpdate = reason
697 cn.handleUpdateRequests()
700 func (cn *PeerConn) handleUpdateRequests() {
701 // The writer determines the request state as needed when it can write.
705 // Emits the indices in the Bitmaps bms in order, never repeating any index.
706 // skip is mutated during execution, and its initial values will never be
708 func iterBitmapsDistinct(skip *bitmap.Bitmap, bms ...bitmap.Bitmap) iter.Func {
709 return func(cb iter.Callback) {
710 for _, bm := range bms {
712 func(_i interface{}) bool {
714 if skip.Contains(bitmap.BitIndex(i)) {
717 skip.Add(bitmap.BitIndex(i))
728 func (cn *Peer) peerPiecesChanged() {
729 cn.t.maybeDropMutuallyCompletePeer(cn)
732 func (cn *PeerConn) raisePeerMinPieces(newMin pieceIndex) {
733 if newMin > cn.peerMinPieces {
734 cn.peerMinPieces = newMin
738 func (cn *PeerConn) peerSentHave(piece pieceIndex) error {
739 if cn.t.haveInfo() && piece >= cn.t.numPieces() || piece < 0 {
740 return errors.New("invalid piece")
742 if cn.peerHasPiece(piece) {
745 cn.raisePeerMinPieces(piece + 1)
746 if !cn.peerHasPiece(piece) {
747 cn.t.incPieceAvailability(piece)
749 cn._peerPieces.Add(uint32(piece))
750 if cn.t.wantPieceIndex(piece) {
751 cn.updateRequests("have")
753 cn.peerPiecesChanged()
757 func (cn *PeerConn) peerSentBitfield(bf []bool) error {
759 panic("expected bitfield length divisible by 8")
761 // We know that the last byte means that at most the last 7 bits are wasted.
762 cn.raisePeerMinPieces(pieceIndex(len(bf) - 7))
763 if cn.t.haveInfo() && len(bf) > int(cn.t.numPieces()) {
764 // Ignore known excess pieces.
765 bf = bf[:cn.t.numPieces()]
767 pp := cn.newPeerPieces()
768 cn.peerSentHaveAll = false
769 for i, have := range bf {
771 cn.raisePeerMinPieces(pieceIndex(i) + 1)
772 if !pp.Contains(bitmap.BitIndex(i)) {
773 cn.t.incPieceAvailability(i)
776 if pp.Contains(bitmap.BitIndex(i)) {
777 cn.t.decPieceAvailability(i)
781 cn._peerPieces.Add(uint32(i))
782 if cn.t.wantPieceIndex(i) {
783 cn.updateRequests("bitfield")
786 cn._peerPieces.Remove(uint32(i))
789 cn.peerPiecesChanged()
793 func (cn *Peer) onPeerHasAllPieces() {
796 npp, pc := cn.newPeerPieces(), t.numPieces()
797 for i := 0; i < pc; i += 1 {
798 if !npp.Contains(bitmap.BitIndex(i)) {
799 t.incPieceAvailability(i)
803 cn.peerSentHaveAll = true
804 cn._peerPieces.Clear()
805 if !cn.t._pendingPieces.IsEmpty() {
806 cn.updateRequests("Peer.onPeerHasAllPieces")
808 cn.peerPiecesChanged()
811 func (cn *PeerConn) onPeerSentHaveAll() error {
812 cn.onPeerHasAllPieces()
816 func (cn *PeerConn) peerSentHaveNone() error {
817 cn.t.decPeerPieceAvailability(&cn.Peer)
818 cn._peerPieces.Clear()
819 cn.peerSentHaveAll = false
820 cn.peerPiecesChanged()
824 func (c *PeerConn) requestPendingMetadata() {
828 if c.PeerExtensionIDs[pp.ExtensionNameMetadata] == 0 {
829 // Peer doesn't support this.
832 // Request metadata pieces that we don't have in a random order.
834 for index := 0; index < c.t.metadataPieceCount(); index++ {
835 if !c.t.haveMetadataPiece(index) && !c.requestedMetadataPiece(index) {
836 pending = append(pending, index)
839 rand.Shuffle(len(pending), func(i, j int) { pending[i], pending[j] = pending[j], pending[i] })
840 for _, i := range pending {
841 c.requestMetadataPiece(i)
845 func (cn *PeerConn) wroteMsg(msg *pp.Message) {
846 torrent.Add(fmt.Sprintf("messages written of type %s", msg.Type.String()), 1)
847 if msg.Type == pp.Extended {
848 for name, id := range cn.PeerExtensionIDs {
849 if id != msg.ExtendedID {
852 torrent.Add(fmt.Sprintf("Extended messages written for protocol %q", name), 1)
855 cn.allStats(func(cs *ConnStats) { cs.wroteMsg(msg) })
858 // After handshake, we know what Torrent and Client stats to include for a
860 func (cn *Peer) postHandshakeStats(f func(*ConnStats)) {
866 // All ConnStats that include this connection. Some objects are not known
867 // until the handshake is complete, after which it's expected to reconcile the
869 func (cn *Peer) allStats(f func(*ConnStats)) {
871 if cn.reconciledHandshakeStats {
872 cn.postHandshakeStats(f)
876 func (cn *PeerConn) wroteBytes(n int64) {
877 cn.allStats(add(n, func(cs *ConnStats) *Count { return &cs.BytesWritten }))
880 func (cn *Peer) readBytes(n int64) {
881 cn.allStats(add(n, func(cs *ConnStats) *Count { return &cs.BytesRead }))
884 // Returns whether the connection could be useful to us. We're seeding and
885 // they want data, we don't have metainfo and they can provide it, etc.
886 func (c *Peer) useful() bool {
888 if c.closed.IsSet() {
892 return c.supportsExtension("ut_metadata")
894 if t.seeding() && c.peerInterested {
897 if c.peerHasWantedPieces() {
903 func (c *Peer) lastHelpful() (ret time.Time) {
904 ret = c.lastUsefulChunkReceived
905 if c.t.seeding() && c.lastChunkSent.After(ret) {
906 ret = c.lastChunkSent
911 func (c *PeerConn) fastEnabled() bool {
912 return c.PeerExtensionBytes.SupportsFast() && c.t.cl.config.Extensions.SupportsFast()
915 func (c *PeerConn) reject(r Request) {
916 if !c.fastEnabled() {
917 panic("fast not enabled")
919 c.write(r.ToMsg(pp.Reject))
920 delete(c.peerRequests, r)
923 func (c *PeerConn) onReadRequest(r Request) error {
924 requestedChunkLengths.Add(strconv.FormatUint(r.Length.Uint64(), 10), 1)
925 if _, ok := c.peerRequests[r]; ok {
926 torrent.Add("duplicate requests received", 1)
930 torrent.Add("requests received while choking", 1)
932 torrent.Add("requests rejected while choking", 1)
937 // TODO: What if they've already requested this?
938 if len(c.peerRequests) >= localClientReqq {
939 torrent.Add("requests received while queue full", 1)
943 // BEP 6 says we may close here if we choose.
946 if !c.t.havePiece(pieceIndex(r.Index)) {
947 // This isn't necessarily them screwing up. We can drop pieces
948 // from our storage, and can't communicate this to peers
949 // except by reconnecting.
950 requestsReceivedForMissingPieces.Add(1)
951 return fmt.Errorf("peer requested piece we don't have: %v", r.Index.Int())
953 // Check this after we know we have the piece, so that the piece length will be known.
954 if r.Begin+r.Length > c.t.pieceLength(pieceIndex(r.Index)) {
955 torrent.Add("bad requests received", 1)
956 return errors.New("bad Request")
958 if c.peerRequests == nil {
959 c.peerRequests = make(map[Request]*peerRequestState, localClientReqq)
961 value := &peerRequestState{}
962 c.peerRequests[r] = value
963 go c.peerRequestDataReader(r, value)
968 func (c *PeerConn) peerRequestDataReader(r Request, prs *peerRequestState) {
969 b, err := readPeerRequestData(r, c)
971 defer c.locker().Unlock()
973 c.peerRequestDataReadFailed(err, r)
976 panic("data must be non-nil to trigger send")
983 // If this is maintained correctly, we might be able to support optional synchronous reading for
984 // chunk sending, the way it used to work.
985 func (c *PeerConn) peerRequestDataReadFailed(err error, r Request) {
986 c.logger.WithDefaultLevel(log.Warning).Printf("error reading chunk for peer Request %v: %v", r, err)
987 i := pieceIndex(r.Index)
988 if c.t.pieceComplete(i) {
989 // There used to be more code here that just duplicated the following break. Piece
990 // completions are currently cached, so I'm not sure how helpful this update is, except to
991 // pull any completion changes pushed to the storage backend in failed reads that got us
993 c.t.updatePieceCompletion(i)
995 // If we failed to send a chunk, choke the peer to ensure they flush all their requests. We've
996 // probably dropped a piece from storage, but there's no way to communicate this to the peer. If
997 // they ask for it again, we'll kick them to allow us to send them an updated bitfield on the
998 // next connect. TODO: Support rejecting here too.
1000 c.logger.WithDefaultLevel(log.Warning).Printf("already choking peer, requests might not be rejected correctly")
1005 func readPeerRequestData(r Request, c *PeerConn) ([]byte, error) {
1006 b := make([]byte, r.Length)
1007 p := c.t.info.Piece(int(r.Index))
1008 n, err := c.t.readAt(b, p.Offset()+int64(r.Begin))
1015 panic("expected error")
1021 func runSafeExtraneous(f func()) {
1029 func (c *PeerConn) logProtocolBehaviour(level log.Level, format string, arg ...interface{}) {
1030 c.logger.WithLevel(level).WithContextText(fmt.Sprintf(
1031 "peer id %q, ext v %q", c.PeerID, c.PeerClientName,
1032 )).SkipCallers(1).Printf(format, arg...)
1035 // Processes incoming BitTorrent wire-protocol messages. The client lock is held upon entry and
1036 // exit. Returning will end the connection.
1037 func (c *PeerConn) mainReadLoop() (err error) {
1040 torrent.Add("connection.mainReadLoop returned with error", 1)
1042 torrent.Add("connection.mainReadLoop returned with no error", 1)
1048 decoder := pp.Decoder{
1049 R: bufio.NewReaderSize(c.r, 1<<17),
1050 MaxLength: 256 * 1024,
1058 err = decoder.Decode(&msg)
1060 if cb := c.callbacks.ReadMessage; cb != nil && err == nil {
1063 if t.closed.IsSet() || c.closed.IsSet() {
1069 c.lastMessageReceived = time.Now()
1071 receivedKeepalives.Add(1)
1074 messageTypesReceived.Add(msg.Type.String(), 1)
1075 if msg.Type.FastExtension() && !c.fastEnabled() {
1076 runSafeExtraneous(func() { torrent.Add("fast messages received when extension is disabled", 1) })
1077 return fmt.Errorf("received fast extension message (type=%v) but extension is disabled", msg.Type)
1084 if !c.fastEnabled() {
1085 c.deleteAllRequests()
1087 // We don't decrement pending requests here, let's wait for the peer to either
1088 // reject or satisfy the outstanding requests. Additionally some peers may unchoke
1089 // us and resume where they left off, we don't want to have piled on to those chunks
1090 // in the meanwhile. I think a peers ability to abuse this should be limited: they
1091 // could let us request a lot of stuff, then choke us and never reject, but they're
1092 // only a single peer, our chunk balancing should smooth over this abuse.
1094 c.peerChoking = true
1095 // We can now reset our interest. I think we do this after setting the flag in case the
1096 // peerImpl updates synchronously (webseeds?).
1097 c.updateRequests("choked")
1098 c.updateExpectingChunks()
1101 // Some clients do this for some reason. Transmission doesn't error on this, so we
1102 // won't for consistency.
1103 c.logProtocolBehaviour(log.Debug, "received unchoke when already unchoked")
1106 c.peerChoking = false
1108 c.actualRequestState.Requests.Iterate(func(x uint32) bool {
1109 if !c.peerAllowedFast.Contains(x / c.t.chunksPerRegularPiece()) {
1114 if preservedCount != 0 {
1115 // TODO: Yes this is a debug log but I'm not happy with the state of the logging lib
1117 c.logger.WithLevel(log.Debug).Printf(
1118 "%v requests were preserved while being choked (fast=%v)",
1121 torrent.Add("requestsPreservedThroughChoking", int64(preservedCount))
1123 c.updateRequests("unchoked")
1124 c.updateExpectingChunks()
1126 c.peerInterested = true
1128 case pp.NotInterested:
1129 c.peerInterested = false
1130 // We don't clear their requests since it isn't clear in the spec.
1131 // We'll probably choke them for this, which will clear them if
1132 // appropriate, and is clearly specified.
1134 err = c.peerSentHave(pieceIndex(msg.Index))
1136 err = c.peerSentBitfield(msg.Bitfield)
1138 r := newRequestFromMessage(&msg)
1139 err = c.onReadRequest(r)
1141 c.doChunkReadStats(int64(len(msg.Piece)))
1142 err = c.receiveChunk(&msg)
1143 if len(msg.Piece) == int(t.chunkSize) {
1144 t.chunkPool.Put(&msg.Piece)
1147 err = fmt.Errorf("receiving chunk: %w", err)
1150 req := newRequestFromMessage(&msg)
1151 c.onPeerSentCancel(req)
1153 ipa, ok := tryIpPortFromNetAddr(c.RemoteAddr)
1157 pingAddr := net.UDPAddr{
1162 pingAddr.Port = int(msg.Port)
1164 cl.eachDhtServer(func(s DhtServer) {
1165 go s.Ping(&pingAddr)
1168 torrent.Add("suggests received", 1)
1169 log.Fmsg("peer suggested piece %d", msg.Index).AddValues(c, msg.Index).SetLevel(log.Debug).Log(c.t.logger)
1170 c.updateRequests("suggested")
1172 err = c.onPeerSentHaveAll()
1174 err = c.peerSentHaveNone()
1176 c.remoteRejectedRequest(c.t.requestIndexFromRequest(newRequestFromMessage(&msg)))
1177 case pp.AllowedFast:
1178 torrent.Add("allowed fasts received", 1)
1179 log.Fmsg("peer allowed fast: %d", msg.Index).AddValues(c).SetLevel(log.Debug).Log(c.t.logger)
1180 c.updateRequests("PeerConn.mainReadLoop allowed fast")
1182 err = c.onReadExtendedMsg(msg.ExtendedID, msg.ExtendedPayload)
1184 err = fmt.Errorf("received unknown message type: %#v", msg.Type)
1192 func (c *Peer) remoteRejectedRequest(r RequestIndex) {
1193 if c.deleteRequest(r) {
1194 if c.isLowOnRequests() {
1195 c.updateRequests("Peer.remoteRejectedRequest")
1197 c.decExpectedChunkReceive(r)
1201 func (c *Peer) decExpectedChunkReceive(r RequestIndex) {
1202 count := c.validReceiveChunks[r]
1204 delete(c.validReceiveChunks, r)
1205 } else if count > 1 {
1206 c.validReceiveChunks[r] = count - 1
1212 func (c *PeerConn) onReadExtendedMsg(id pp.ExtensionNumber, payload []byte) (err error) {
1214 // TODO: Should we still do this?
1216 // These clients use their own extension IDs for outgoing message
1217 // types, which is incorrect.
1218 if bytes.HasPrefix(c.PeerID[:], []byte("-SD0100-")) || strings.HasPrefix(string(c.PeerID[:]), "-XL0012-") {
1226 case pp.HandshakeExtendedID:
1227 var d pp.ExtendedHandshakeMessage
1228 if err := bencode.Unmarshal(payload, &d); err != nil {
1229 c.logger.Printf("error parsing extended handshake message %q: %s", payload, err)
1230 return fmt.Errorf("unmarshalling extended handshake payload: %w", err)
1232 if cb := c.callbacks.ReadExtendedHandshake; cb != nil {
1235 //c.logger.WithDefaultLevel(log.Debug).Printf("received extended handshake message:\n%s", spew.Sdump(d))
1237 c.PeerMaxRequests = d.Reqq
1239 c.PeerClientName = d.V
1240 if c.PeerExtensionIDs == nil {
1241 c.PeerExtensionIDs = make(map[pp.ExtensionName]pp.ExtensionNumber, len(d.M))
1243 c.PeerListenPort = d.Port
1244 c.PeerPrefersEncryption = d.Encryption
1245 for name, id := range d.M {
1246 if _, ok := c.PeerExtensionIDs[name]; !ok {
1247 peersSupportingExtension.Add(string(name), 1)
1249 c.PeerExtensionIDs[name] = id
1251 if d.MetadataSize != 0 {
1252 if err = t.setMetadataSize(d.MetadataSize); err != nil {
1253 return fmt.Errorf("setting metadata size to %d: %w", d.MetadataSize, err)
1256 c.requestPendingMetadata()
1257 if !t.cl.config.DisablePEX {
1258 t.pex.Add(c) // we learnt enough now
1262 case metadataExtendedId:
1263 err := cl.gotMetadataExtensionMsg(payload, t, c)
1265 return fmt.Errorf("handling metadata extension message: %w", err)
1269 if !c.pex.IsEnabled() {
1270 return nil // or hang-up maybe?
1272 return c.pex.Recv(payload)
1274 return fmt.Errorf("unexpected extended message ID: %v", id)
1278 // Set both the Reader and Writer for the connection from a single ReadWriter.
1279 func (cn *PeerConn) setRW(rw io.ReadWriter) {
1284 // Returns the Reader and Writer as a combined ReadWriter.
1285 func (cn *PeerConn) rw() io.ReadWriter {
1292 func (c *Peer) doChunkReadStats(size int64) {
1293 c.allStats(func(cs *ConnStats) { cs.receivedChunk(size) })
1296 // Handle a received chunk from a peer.
1297 func (c *Peer) receiveChunk(msg *pp.Message) error {
1298 chunksReceived.Add("total", 1)
1300 ppReq := newRequestFromMessage(msg)
1301 req := c.t.requestIndexFromRequest(ppReq)
1304 chunksReceived.Add("while choked", 1)
1307 if c.validReceiveChunks[req] <= 0 {
1308 chunksReceived.Add("unexpected", 1)
1309 return errors.New("received unexpected chunk")
1311 c.decExpectedChunkReceive(req)
1313 if c.peerChoking && c.peerAllowedFast.Contains(bitmap.BitIndex(ppReq.Index)) {
1314 chunksReceived.Add("due to allowed fast", 1)
1317 // The request needs to be deleted immediately to prevent cancels occurring asynchronously when
1318 // have actually already received the piece, while we have the Client unlocked to write the data
1320 deletedRequest := false
1322 if c.actualRequestState.Requests.Contains(req) {
1323 for _, f := range c.callbacks.ReceivedRequested {
1324 f(PeerMessageEvent{c, msg})
1327 // Request has been satisfied.
1328 if c.deleteRequest(req) {
1329 deletedRequest = true
1331 c._chunksReceivedWhileExpecting++
1333 if c.isLowOnRequests() {
1334 c.updateRequests("Peer.receiveChunk deleted request")
1337 chunksReceived.Add("unwanted", 1)
1344 // Do we actually want this chunk?
1345 if t.haveChunk(ppReq) {
1346 //panic(fmt.Sprintf("%+v", ppReq))
1347 chunksReceived.Add("wasted", 1)
1348 c.allStats(add(1, func(cs *ConnStats) *Count { return &cs.ChunksReadWasted }))
1352 piece := &t.pieces[ppReq.Index]
1354 c.allStats(add(1, func(cs *ConnStats) *Count { return &cs.ChunksReadUseful }))
1355 c.allStats(add(int64(len(msg.Piece)), func(cs *ConnStats) *Count { return &cs.BytesReadUsefulData }))
1357 c.piecesReceivedSinceLastRequestUpdate++
1358 c.allStats(add(int64(len(msg.Piece)), func(cs *ConnStats) *Count { return &cs.BytesReadUsefulIntendedData }))
1360 for _, f := range c.t.cl.config.Callbacks.ReceivedUsefulData {
1361 f(ReceivedUsefulDataEvent{c, msg})
1363 c.lastUsefulChunkReceived = time.Now()
1365 // Need to record that it hasn't been written yet, before we attempt to do
1366 // anything with it.
1367 piece.incrementPendingWrites()
1368 // Record that we have the chunk, so we aren't trying to download it while
1369 // waiting for it to be written to storage.
1370 piece.unpendChunkIndex(chunkIndexFromChunkSpec(ppReq.ChunkSpec, t.chunkSize))
1372 // Cancel pending requests for this chunk from *other* peers.
1373 t.iterPeers(func(p *Peer) {
1380 err := func() error {
1383 concurrentChunkWrites.Add(1)
1384 defer concurrentChunkWrites.Add(-1)
1385 // Write the chunk out. Note that the upper bound on chunk writing concurrency will be the
1386 // number of connections. We write inline with receiving the chunk (with this lock dance),
1387 // because we want to handle errors synchronously and I haven't thought of a nice way to
1388 // defer any concurrency to the storage and have that notify the client of errors. TODO: Do
1390 return t.writeChunk(int(msg.Index), int64(msg.Begin), msg.Piece)
1393 piece.decrementPendingWrites()
1396 c.logger.WithDefaultLevel(log.Error).Printf("writing received chunk %v: %v", req, err)
1398 // Necessary to pass TestReceiveChunkStorageFailureSeederFastExtensionDisabled. I think a
1399 // request update runs while we're writing the chunk that just failed. Then we never do a
1400 // fresh update after pending the failed request.
1401 c.updateRequests("Peer.receiveChunk error writing chunk")
1402 t.onWriteChunkErr(err)
1406 c.onDirtiedPiece(pieceIndex(ppReq.Index))
1408 // We need to ensure the piece is only queued once, so only the last chunk writer gets this job.
1409 if t.pieceAllDirty(pieceIndex(ppReq.Index)) && piece.pendingWrites == 0 {
1410 t.queuePieceCheck(pieceIndex(ppReq.Index))
1411 // We don't pend all chunks here anymore because we don't want code dependent on the dirty
1412 // chunk status (such as the haveChunk call above) to have to check all the various other
1413 // piece states like queued for hash, hashing etc. This does mean that we need to be sure
1414 // that chunk pieces are pended at an appropriate time later however.
1417 cl.event.Broadcast()
1418 // We do this because we've written a chunk, and may change PieceState.Partial.
1419 t.publishPieceChange(pieceIndex(ppReq.Index))
1424 func (c *Peer) onDirtiedPiece(piece pieceIndex) {
1425 if c.peerTouchedPieces == nil {
1426 c.peerTouchedPieces = make(map[pieceIndex]struct{})
1428 c.peerTouchedPieces[piece] = struct{}{}
1429 ds := &c.t.pieces[piece].dirtiers
1431 *ds = make(map[*Peer]struct{})
1433 (*ds)[c] = struct{}{}
1436 func (c *PeerConn) uploadAllowed() bool {
1437 if c.t.cl.config.NoUpload {
1440 if c.t.dataUploadDisallowed {
1446 if !c.peerHasWantedPieces() {
1449 // Don't upload more than 100 KiB more than we download.
1450 if c._stats.BytesWrittenData.Int64() >= c._stats.BytesReadData.Int64()+100<<10 {
1456 func (c *PeerConn) setRetryUploadTimer(delay time.Duration) {
1457 if c.uploadTimer == nil {
1458 c.uploadTimer = time.AfterFunc(delay, c.tickleWriter)
1460 c.uploadTimer.Reset(delay)
1464 // Also handles choking and unchoking of the remote peer.
1465 func (c *PeerConn) upload(msg func(pp.Message) bool) bool {
1466 // Breaking or completing this loop means we don't want to upload to the
1467 // peer anymore, and we choke them.
1469 for c.uploadAllowed() {
1470 // We want to upload to the peer.
1471 if !c.unchoke(msg) {
1474 for r, state := range c.peerRequests {
1475 if state.data == nil {
1478 res := c.t.cl.config.UploadRateLimiter.ReserveN(time.Now(), int(r.Length))
1480 panic(fmt.Sprintf("upload rate limiter burst size < %d", r.Length))
1482 delay := res.Delay()
1485 c.setRetryUploadTimer(delay)
1486 // Hard to say what to return here.
1489 more := c.sendChunk(r, msg, state)
1490 delete(c.peerRequests, r)
1501 func (cn *PeerConn) drop() {
1502 cn.t.dropConnection(cn)
1505 func (cn *Peer) netGoodPiecesDirtied() int64 {
1506 return cn._stats.PiecesDirtiedGood.Int64() - cn._stats.PiecesDirtiedBad.Int64()
1509 func (c *Peer) peerHasWantedPieces() bool {
1510 if c.peerSentHaveAll {
1511 return !c.t.haveAllPieces()
1513 if !c.t.haveInfo() {
1514 return !c._peerPieces.IsEmpty()
1516 return c._peerPieces.Intersects(&c.t._pendingPieces)
1519 func (c *Peer) deleteRequest(r RequestIndex) bool {
1520 if !c.actualRequestState.Requests.CheckedRemove(r) {
1523 c.cancelledRequests.Remove(r)
1524 for _, f := range c.callbacks.DeletedRequest {
1525 f(PeerRequestEvent{c, c.t.requestIndexToRequest(r)})
1527 c.updateExpectingChunks()
1528 c.t.pendingRequests.Dec(r)
1532 func (c *Peer) deleteAllRequests() {
1533 c.actualRequestState.Requests.Clone().Iterate(func(x uint32) bool {
1537 if !c.actualRequestState.Requests.IsEmpty() {
1538 panic(c.actualRequestState.Requests.GetCardinality())
1542 // This is called when something has changed that should wake the writer, such as putting stuff into
1543 // the writeBuffer, or changing some state that the writer can act on.
1544 func (c *PeerConn) tickleWriter() {
1545 c.messageWriter.writeCond.Broadcast()
1548 func (c *PeerConn) sendChunk(r Request, msg func(pp.Message) bool, state *peerRequestState) (more bool) {
1549 c.lastChunkSent = time.Now()
1550 return msg(pp.Message{
1558 func (c *PeerConn) setTorrent(t *Torrent) {
1560 panic("connection already associated with a torrent")
1563 c.logger.WithDefaultLevel(log.Debug).Printf("set torrent=%v", t)
1564 t.reconcileHandshakeStats(c)
1567 func (c *Peer) peerPriority() (peerPriority, error) {
1568 return bep40Priority(c.remoteIpPort(), c.t.cl.publicAddr(c.remoteIp()))
1571 func (c *Peer) remoteIp() net.IP {
1572 host, _, _ := net.SplitHostPort(c.RemoteAddr.String())
1573 return net.ParseIP(host)
1576 func (c *Peer) remoteIpPort() IpPort {
1577 ipa, _ := tryIpPortFromNetAddr(c.RemoteAddr)
1578 return IpPort{ipa.IP, uint16(ipa.Port)}
1581 func (c *PeerConn) pexPeerFlags() pp.PexPeerFlags {
1582 f := pp.PexPeerFlags(0)
1583 if c.PeerPrefersEncryption {
1584 f |= pp.PexPrefersEncryption
1587 f |= pp.PexOutgoingConn
1590 f |= pp.PexSupportsUtp
1595 // This returns the address to use if we want to dial the peer again. It incorporates the peer's
1596 // advertised listen port.
1597 func (c *PeerConn) dialAddr() PeerRemoteAddr {
1598 if !c.outgoing && c.PeerListenPort != 0 {
1599 switch addr := c.RemoteAddr.(type) {
1602 dialAddr.Port = c.PeerListenPort
1606 dialAddr.Port = c.PeerListenPort
1613 func (c *PeerConn) pexEvent(t pexEventType) pexEvent {
1614 f := c.pexPeerFlags()
1615 addr := c.dialAddr()
1616 return pexEvent{t, addr, f}
1619 func (c *PeerConn) String() string {
1620 return fmt.Sprintf("connection %p", c)
1623 func (c *Peer) trust() connectionTrust {
1624 return connectionTrust{c.trusted, c.netGoodPiecesDirtied()}
1627 type connectionTrust struct {
1629 NetGoodPiecesDirted int64
1632 func (l connectionTrust) Less(r connectionTrust) bool {
1633 return multiless.New().Bool(l.Implicit, r.Implicit).Int64(l.NetGoodPiecesDirted, r.NetGoodPiecesDirted).Less()
1636 // Returns the pieces the peer could have based on their claims. If we don't know how many pieces
1637 // are in the torrent, it could be a very large range the peer has sent HaveAll.
1638 func (cn *PeerConn) PeerPieces() *roaring.Bitmap {
1640 defer cn.locker().RUnlock()
1641 return cn.newPeerPieces()
1644 // Returns a new Bitmap that includes bits for all pieces the peer could have based on their claims.
1645 func (cn *Peer) newPeerPieces() *roaring.Bitmap {
1646 // TODO: Can we use copy on write?
1647 ret := cn._peerPieces.Clone()
1648 if cn.peerSentHaveAll {
1649 if cn.t.haveInfo() {
1650 ret.AddRange(0, bitmap.BitRange(cn.t.numPieces()))
1652 ret.AddRange(0, bitmap.ToEnd)
1658 func (cn *Peer) stats() *ConnStats {
1662 func (p *Peer) TryAsPeerConn() (*PeerConn, bool) {
1663 pc, ok := p.peerImpl.(*PeerConn)
1667 func (pc *PeerConn) isLowOnRequests() bool {
1668 return pc.actualRequestState.Requests.IsEmpty()